The present invention relates to metal pressure shaping machinery and more particularly to profile plano-type knurling machines.
The present invention can be more successively used for shaping splines on shafts, teeth of gears, polygonal pieces and so on.
Known in the prior art are profile plano-type knurling machines (cfr USSR Inventor's Certificate No. 350,553, Cl.B21h 7/14) wherein mounted between fixed support members carrying movable and fixed centers for placing the work piece and rigidly connected to each other by ways is a movable support member with a possibility for reciprocations along said ways carrying a knurling head being coaxial to the centers and having knurl rollers and there is a device for moving the knurl rollers in the radial direction relative to the centers, comprising tapered elements mounted in the knurling head with a possibility for adjustment movements in the axial direction relative to the centers and kinematically associated with the knurl rollers and pressure members actuating the tapered elements in the extreme positions of the movable support member for a radial feed of the knurl rollers and their return to the starting position.
Said device for the radial feed of the knurl rollers and their return to the starting position in the known knurling machines has pressure members made in the form of bars rigidly secured onto the fixed support members. Each of these bars is installed in front of the apex or base of one of the tapered elements in such a way that their axes parallel to the centers.
The radial feed of the knurl rollers is performed prior to each working travel of the movable support member with the knurling head. The movable support member is moved towards the fixed traverse facing the bases of the tapered elements. In the course of movement of the movable support member near its extreme position the butt of the free end of each bar installed on said fixed support member actuates the base of a respective tapered element. The bar actuates this tapered element to move it in the axial direction relative to the centers.
The knurling head has a housing provided with radial slots. Each of these slots accommodates a slider with the knurl roller and the tapered element of said device associated kinematically therewith and installed between the bottom of the slot and the slider.
When the tapered element moves its inclined surface actuates the inclined surface of the slider, thus moving said slider with the knurl roller in the radial slot towards the work piece at a distance equal to a preset value of the radial feed of the knurl rollers.
After the knurl rollers are fed radially, one progressive motion of the movable support members with the knurling head is performed. In the course of this motion of the movable support member with the knurling head the knurl rollers start processing the workpiece thus shaping the profile elements to a depth relative to the value of the first radial feed of the knurl rollers. This motion is a working travel. In the course of the backward travel of the movable traverse with the knurling head the knurl rollers start processing the work piece only in the range of the resilient deformations and therefore this motion of the movable support member is an idle travel. These reciprocations of the movable support member repeat until the profile elements are fully shaped. At the end of each backward travel of the movable support member with the knurling head whose length increases constantly the bars actuate the tapered elements whereas said bars move the tapered elements to a distance relative to the value of the radial feed of the knurl rollers for shaping the profile at a working travel of the movable support member with the knurling head.
When the profile shaping cycle has been finished the movable support member with the knurling head is stopped in the starting position. The processed work piece is removed from the working area.
The knurl rollers return their home position. For the purpose the movable support member with the knurling head is moved towards the fixed support member facing the apeces of the tapered elements. At the end of this travel the pressure members secured onto this fixed support member actuate the apeces of the tapered element, thus moving these tapered elements in the axial direction relative to the centers towards their bases.
The sliders with the knurl rollers are pressed by compression springs to the tapered elements and therefore when the cotters move towards their bases the sliders with the knurl rollers are moved in the radial slots from the centers and thus return their home position.
Prior to knurling a work piece of a defined dimension the bars should be adjusted to a preset height. Since the known knurling machines are provided with a comparatively great amount of these bars which at the same time should be adjusted accurately with a minimum difference in height from each other to obtain the preset accuracy of the profile elements in the course of knurling, the adjustment cycle of these knurling machines is sufficiently laborous and requires much time.
This complicated adjustment of the knurling machine does not provide as a rule for the preset accuracy of the radial feed of knurl rollers, thus decreasing the accuracy of the profile elements being knurled.
As a result the knurled profiles should be worked additionally to correct their geometrical dimensions and achieve the preset accuracy. These additional operations increase substantially the labour in the manufacture of the profiles, require the application of additional equipment for performing same.
Idle travels of the movable support member with the knurling head and compartively laborous adjustment of the knurling machine reduce greatly the efficiency thereof.
In addition, the great amount of pressure members and possible optional motions of tapered elements and therefore the knurl rollers in the course of knurling reduce greatly the operational reliability of the known knurling machine and the accuracy of the work piece being processed.